This is competitive renewal of Molecular Biophysics Training Grant program at Harvard University which seeks to provide rigorous multi- disciplinary training in a broad range of biophysical techniques relevant to biological and biomedical problems. The training program supports students from three graduate programs in Biophysics, Chemistry and Chemical Biology, and Biological and Biomedical Sciences and links 31 faculty from four departments in the Faculty of Arts and Sciences, and five departments and four affiliated hospitals in the Division of Medical Sciences at Harvard Medical School. This application requests support for 16 training positions of which 10 will be allocated to students entering the Biophysics program, 4 will be allocated to students entering the BBS program, and 2 will be allocated to students entering the graduate program in Chemistry and Chemical Biology. The training grant program was originally conceived as an opportunity to take advantage of an increasing focus on chemical biology in the Department of Chemistry, a significant expansion of an already strong structural biology community, and a renewed focus on basic research at Harvard Medical School to expand the scope and impact of graduate training and research in molecular biophysics. This program has been highly successful in promoting collaborative research among its faculty and interdisciplinary graduate training at the interface between structural molecular biology and chemistry. In the next funding period we believe that the training program is similarly poised to take advantage of exciting new developments which formalize interactions between structural biology, chemical biology and cell biology within Harvard University to further increase the scope and impact of training in molecular biophysics.